Interlock mechanism for range section slave valve

ABSTRACT

A fluid pressure actuated auxiliary transmission section (14) shift control system (230)/method is provided which includes control members (246, 328) to prevent auxiliary section synchronized clutch (92, 128) damage if the main transmission section (12) is engaged during an auxiliary section shift. A range interlock assembly (258) is provided which will release the range slave valve (238) as the main transmission section is shifted toward the neutral position thereof.

BACKGROUND OF THE INVENTION Related Applications

This application is related to copending U.S. patent applications:

Ser .No. 824,924, entitled AUXILIARY SECTION ACTUATOR CONTROL SYSTEM ANDMETHOD;

Ser. No. 824,675, entitled RANGE VALVE PRE-EXHAUST;

Ser. No. 824,961, entitled TWO-STAGE RANGE PISTON/CYLINDER ASSEMBLY;

Ser. No. 824,645, entitled VARIABLE PRESSURE RANGE SECTION ACTUATORPISTON;

Ser. No. 824,960, entitled DUAL PRESSURE REGULATOR;

Ser. No. 824,672, entitled VARIABLE PRESSURE RANGE SECTION ACTUATORASSEMBLY;

Ser. No. 824,638, entitled RANGE SECTION ACTUATOR CONTROL SYSTEM ANDMETHOD FOR PREVENTING DAMAGE TO RANGE SECTION SYNCHRONIZERS;

Ser. No. 824,925, entitled RANGE SECTION PROTECTION VALVE ASSEMBLY; and

Ser. No. 824,956, entitled SYNCHRONIZED SPLITTER SECTION PROTECTIONSYSTEM/METHOD;

all assigned to the same assignee, Eaton Corporation, and filed the sameday, Jan. 23, 1992, as this application.

Field of the Invention

The present invention relates to a mechanism and/or method forcontrolling the auxiliary section actuator of a vehicular compoundtransmission. In particular, the present invention relates topressurized fluid (pneumatic) system and/or method for controlling theengagement of auxiliary section synchronized jaw clutches in compoundtransmissions of the type comprising one or more multiple speedauxiliary transmission sections connected in series with a multiplespeed main transmission section. More particularly, the presentinvention relates to a pressurized fluid (pneumatic) control systemand/or method utilizing an improved interlock system for protecting theauxiliary section synchronized jaw clutches of a compound heavy dutyvehicular transmission during a compound shift.

Description of the Prior Art

Compound change gear transmissions of the type having one or moreauxiliary sections connected in series with a main transmission sectionare very well known in the prior art. Such transmissions are typicallyassociated with heavy duty vehicles such as large trucks,tractor/semi-trailers, and the like. Briefly, by utilizing main andauxiliary transmission sections connected in series, assuming properrelative sizing of the ratio steps, the total of available transmissionratios is equal to the product of the main and auxiliary section ratios.By way of example, at least in theory, a compound change geartransmission comprising a four (4) speed main section connected inseries with a three (3) speed auxiliary section will Provide twelve(4×3=12) available ratios.

Auxiliary transmission sections are of three general types: range type,splitter type or combined range/splitter type.

In compound transmissions having a range type auxiliary section, therange section ratio step or steps are greater than the total ratiocoverage of the main transmission section and the main section isshifted progressively through its ratios in each range. Examples ofcompound transmissions having range type auxiliary sections may be seenby reference to U.S. Pat. Nos. 4,974,474; 4,964,313, 4,920,815;3,105,395; 2,637,222 and 2,637,221, the disclosures of which are herebyincorporated by reference.

Assignee's well known RT/RTO 11609 and RT/RTO 11610 "Roadranger"transmissions are examples of a "(4+1)×(2)", nine speed and "(5)×(2)"ten speed heavy duty range type transmissions.

In compound transmissions having a splitter type auxiliary section, theratio steps of the splitter auxiliary section are less than the ratiosteps of the main transmission section and each main section ratio issplit, or subdivided, by the splitter section. Examples of compoundchange gear transmissions having splitter type auxiliary sections may beseen by reference to U.S. Pat. Nos. 4,290,515; 3,799,002; 4,440,037 and4,527,447, the disclosures of which are hereby incorporated byreference.

In a combined range and splitter type auxiliary section, or sections,both range and splitter type ratios are provided allowing the mainsection to be progressively shifted through its ratios in at least tworanges and also allowing the main section ratios to be split in at leastone range.

One example of a compound transmission having a single combinedrange/splitter type auxiliary section be seen by reference to U.S. Pat.Nos. 3,283,613; 3,648,546, the disclosures of which are herebyincorporated by reference. A three gear layer, four-speed combinedsplitter/range type auxiliary section may be seen by reference to U.S.Pat. No. 4,754,665, the disclosure of which is hereby incorporated byreference. Assignee's well known RT/RTO 11613 and RT/RTO 14718 "EatonRoadranger" transmissions are examples of a "(4+1)×(3)" thirteen-speedand a "(4+1)×(4)" eighteen-speed combined range/splitter typetransmission.

Another example is the "Ecosplit" model of transmission sold byZahnradfabrik Friedrichshafen Aktiengeseushaft of Friedrichshafen,Federal Republich of Germany which utilizes a separate splitterauxiliary section in front of, and a separate range auxiliary sectionbehind, the main transmission section.

It should be noted that the terms main and auxiliary sections arerelative and that if the designations of the main and auxiliary sectionsare reversed, the type of auxiliary section (either range or splitter)will also be reversed. In other words, given what is conventionallyconsidered a four-speed main section with two-speed range type auxiliarysection, if the normally designated auxiliary is considered the mainsection, the normally designated main section would be considered afour-speed splitter type auxiliary section therefor. By generallyaccepted transmission industry convention, and as used in thisdescription of the invention, the main transmission section of acompound transmission is that section which contains the largest (or atleast no less) number of forward speed ratios, which allows section of aneutral position, which contains the reverse ratio(s) and/or which isshifted (in manual or semiautomatic transmissions) by manipulation of ashift bar or shift rail or shift shaft/shift finger assembly as opposedto master/slave valve/cylinder arrangements or the like.

In compound transmissions of the range or the combined range/splitter orsplitter/range types, the main transmission section is typically shiftedby means of a shift bar housing assembly, or single shift shaftassembly, controlled by a manually operated shift lever or the like andthe auxiliary range section is shifted, in "repeat H" typetransmissions, by means of button or switch, usually manually operated,which controls a remote slave valve/actuator mechanism. In so-called"double H" or "one and one-half H" type controls, the range is shiftedby switches responsive to positioning of the shift lever. Double H typecontrols are well known in the prior art as may be seen by reference toU.S. Patents Nos. 4,633,725 and 4,275,612, the disclosures of which areincorporated hereby by reference.

As the range section often utilizes synchronized jaw clutches, toprovide acceptable shift quality and prevent undue wear and/or damage tothe range section synchronized jaw clutches, it has been an object ofthe prior art to provide devices to assure that a range shift beinitiated and hopefully completed while the main transmission section isin neutral.

In view of the above, the prior art compound range type transmissionsusually include a control system, usually a pneumatic control system,including interlock devices, which allowed a range shift to bepreselected by use of a selector button or switch at a master controlvalve but not initiated until the main transmission section is shiftedto, or at least towards, the neutral condition. Such systems typicallyutilized interlocks of the mechanical type on the range section actuatormechanical linkage which physically prevented movement of the rangesection shift fork until the main section shifted into neutral or of thetype wherein the valve (often called the "slave valve") supplyingpressurized air to the range section pistons is either disabled or notprovided with pressurized fluid until a shift to main section neutral issensed, or is only activated and provided with pressurized fluid whilethe main section is shifted to and remains in neutral. Examples of suchtransmissions and the control systems therefor may be seen by referenceto U.S. Pat. Nos. 2,654,268; 3,138,965 and 4,060,005, the disclosures ofwhich are hereby incorporated by reference. Transmissions using rangesection control valves (supply and/or exhaust) which are interlockeduntil a main section shift to neutral occurs may be seen by reference toU.S. Pat. Nos. 3,229,551; 4,450,869; 4,793,378 and 4,974,474, thedisclosures of which are incorporated by reference.

While the prior art systems do provide considerable protection for therange section synchronizers by preventing initiation of a range shiftuntil the main section is shifted into neutral, they are not totallysatisfactory as while they assure that a range section shift will notinitiate until the main section is in neutral, they do not prevent thecondition wherein the main section shift is faster than (i.e. "beats")the range shift. As is well known, under certain conditions, if therange synchronized clutch attempts to engage while main section isengaged, a portion of the engine torque is transferred to the vehiculardrive wheels entirely by the engaged synchronizer friction surfaces andthe synchronizer friction members can be rapidly damaged. In suchcondition, the range synchronizers, especially the direct or high speedrange synchronizer may be damaged or destroyed relatively quickly. Inthe event of an unintended attempt to make a range only shift, suchdamage may occur within about two (2.0) seconds.

Transmissions utilizing mechanical interlock devices, of both the rigidand the resilient type, may be seen by reference to U.S. Pat. Nos.4,974,474; 4,944,197 and 4,296,642, the disclosures of which are herebyincorporated by reference. Such devices typically locked the rangeclutch into high or low position while the main section is not inneutral and/or locked the main section in neutral if the range clutchwas not engaged in the high or low speed position thereof. While thesesystems will, when operating properly, prevent damage to the rangesynchronizers caused by attempting to engage a range clutch while themain section is not in neutral, they were not totally satisfactory as(i) a fast main section shift can result in the auxiliary section beinglocked in an undesirable ratio, (ii) if a range clutch is hung up on theblocker the main section cannot be engaged to manipulate the clutches,(iii) resilient devices may not properly interlock or may bind, (iv)considerable wear and stress may be caused to the interlock and/or shiftactuator members and/or (v) with wear, friction locks of the interlockmechanisms may occur.

SUMMARY OF THE INVENTION

In accordance with the present invention, the drawbacks of the prior artare minimized or overcome by the provision of a pressurized fluidactuated auxiliary section actuator control system and method which willprotect the auxiliary section synchronizers by interlocking the maintransmission section until the auxiliary section shift is complete andwhich allows the actuator chambers to be pressurized and exhausted if anauxiliary section shift is preselected and the main transmission sectionis shifted towards neutral to provide a more rapid auxiliary sectionshift. A more rapid auxiliary section shift will minimize thepossibility of a main section shift beating the auxiliary section andwill also minimize the time that the main section is locked in theneutral position.

The above is accomplished by structuring the range valve interlock suchthat the valve element (spool) will be released as the main sectionshift mechanism moves toward the neutral position thereof rather thanrequiring the main section to shift completely into the neutral positionthereof prior to releasing the interlock. A separate rail interlockmechanism may be provided which locks the auxiliary section in acurrently engaged ratio when the main section is engaged and which locksthe main section in neutral when the auxiliary section is in a shifttransient.

Accordingly, it is an object of the present invention to provide a newand improved auxiliary section (range) shifting control system for acompound transmission of the type utilizing synchronized jaw clutches inthe auxiliary sections thereof.

Another object of the present invention is to provide pressurized fluidactuated auxiliary section actuator control system/method for engagementof a selected auxiliary section synchronized clutches with improvedinterlock means allowing the actuator chambers to be pressurized andexhausted as required to accomplish a preselected shift as the maintransmission section is shifted toward the neutral position thereof.

These and other objects and advantages of the present invention willbecome apparent from a reading of the detailed description of thepreferred embodiment taken in connection with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a compound transmission having arange type auxiliary section and utilizing the pneumatic control systemof the present invention.

FIG. 1A is a schematic illustration of the shifting mechanisms of thetransmission of FIG. 1.

FIG. 1B is a schematic illustration of the "repeat H" type shift patternof the transmission of FIG. 1.

FIG. 1C is a schematic illustration of a "double H" type shift patternfor the transmission of FIG. 1 and,

FIG. 2A are, respectively, compound transmission and the "repeat H"pattern having a combined splitter/range type auxiliary section withwhich the pneumatic control system of the present invention isparticularly useful.

FIG. 3 (A and B) is a partial view, in cross-section, of the auxiliarysection 102 of transmission 100.

FIG. 4 is a prospective view of a single shift shaft type shiftingmechanism.

FIG. 5 is a schematic illustration of an air control system forimplementing the present invention.

FIGS. 6A-6D are schematic illustrations of portions of the air controlsystem of FIG. 5 in various operational positions thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Certain terminology will be used in the following description forconvenience in reference only and will not be limiting. The words"upwardly", "downwardly", "rightwardly", and "leftwardly" will designatedirections in the drawings to which reference is made. The words"forward", "rearward", will refer respectively to the front and rearends of the transmission as conventionally mounted in a vehicle, beingrespectfully from left and right sides of the transmission asillustrated in FIG. 1. The words "inwardly" and "outwardly" will referto directions toward and away from, respectively, the geometric centerof the device and designated parts thereof. Said terminology willinclude the words above specifically mentioned, derivatives thereof andwords of similar import.

The term "compound transmission" is used to designate a change speed orchange gear transmission having a multiple forward speed maintransmission section and a multiple speed auxiliary transmission sectionconnected in series whereby the selected gear reduction in the maintransmission section may be compounded by further selected gearreduction in the auxiliary transmission section. "Synchronized clutchassembly" and words of similar import shall designate a positive,jaw-type clutch assembly utilized to nonrotatably couple a selected gearto a shaft by means of a positive clutch in which attempted engagementof said clutch is prevented until the members of the clutch are atsubstantially synchronous rotation and relatively large capacityfriction means are utilized with the clutch members and are sufficient,upon initiation of a clutch engagement, to cause the clutch members andall members rotating therewith to rotate at substantially synchronousspeed.

The terms "neutral" and "not engaged" are used interchangeably and referto a main transmission section condition wherein torque is nottransferred from the transmission input shaft to the mainshaft (intransmissions of the general type illustrated in FIGS. 1 and 2). Theterms "not neutral" and "engaged" are used interchangeably and refer toa main transmission section condition wherein a main section drive ratiois engaged and drive torque is transferred from the transmission inputshaft to the main shaft (in transmissions of the general typeillustrated in FIGS. 1 and 2).

The term "high speed" ratio refers to that ratio of a transmissionsection wherein the rotational speed of the output is greatest for agiven input rotational speed.

Referring to FIGS. 1, 1A and 1B, a range type compound transmission 10is illustrated. Compound transmission 10 comprises a multiple speed maintransmission section 12 connected in series with a range type auxiliarysection 14. Transmission 10 is housed within a housing H and includes aninput shaft 16 driven by a prime mover such as diesel engine E through aselectively disengaged, normally engaged friction master clutch C havingan input or driving portion 18 drivingly connected to the enginecrankshaft 20 and a driven portion 22 rotatably fixed to thetransmission input shaft 16.

In main transmission section 12, the input shaft 16 carries an inputgear 24 for simultaneously driving a plurality of substantiallyidentical countershaft assemblies 26 and 26A at substantially identicalrotational speeds. The two substantially identical countershaftassemblies are provided on diametrically opposite sides of mainshaft 28which is generally coaxially aligned with the input shaft 16. Each ofthe countershaft assemblies comprises a countershaft 30 supported bybearings 32 and 34 in housing H, only a portion of which isschematically illustrated. Each of the countershafts is provided with anidentical grouping of countershaft gears 38, 40, 42, 4, 46 and 48, fixedfor rotation therewith. A plurality of mainshaft gears 50, 52, 54, 56and 58 surround the mainshaft 28 and are selectively clutchable, one ata time, to the mainshaft 28 for rotation therewith by sliding clutchcollars 60, 62 and 64 as is well known in the prior art. Clutch collar60 may also be utilized to clutch input gear 24 to mainshaft 28 toprovide a direct drive relationship between input shaft 16 and mainshaft28.

Typically, clutch collars 60, 62 and 64 are axially positioned by meansof shift forks 60A, 62A and 64A, respectively, associated with the shifthousing assembly 70, as well known in the prior art. Clutch collars 60,62 and 64 may be of the well known synchronized or nonsynchronizeddouble acting jaw clutch type.

Mainshaft gear 58 is the reverse gear and is in continuous meshingengagement with countershaft gears 48 by means of conventionalintermediate idler gears (not shown). It should also be noted that whilemain transmission section 12 does provide five selectable forward speedratios, the lowest forward speed ratio, namely that provided bydrivingly connecting mainshaft drive gear 56 to mainshaft 28, is oftenof such a high gear reduction it has to be considered a low or "creeper"gear which is utilized only for starting of a vehicle under severeconditions and is not usually utilized in the high transmission range.Accordingly, while main transmission section 12 does provide fiveforward speeds, it is usually referred to as a "four plus one" or"(4+1)" main section as only four of the forward speeds are compoundedby the auxiliary range transmission section 14 utilized therewith.

Jaw clutches 60, 62, and 64 are three-position clutches in that they maybe positioned in the centered, nonengaged position as illustrated, or ina fully rightwardly engaged or fully leftwardly engaged position bymeans of a shift lever 72. As is well known, only one of the clutches60, 62 and 64 is engageable at a given time and main section interlockmeans (not shown) are provided to lock the other clutches in the neutralcondition.

Auxiliary transmission range section 14 includes two substantiallyidentical auxiliary countershaft assemblies 74 and 74A, each comprisingan auxiliary countershaft 76 supported by bearings 78 and 80 in housingH and carrying two auxiliary section countershaft gears 82 and 84 forrotation therewith. Auxiliary countershaft gears 82 are constantlymeshed with and support range/output gear 86 which is fixed for rotationwith mainshaft 28 while auxiliary section countershaft gears 84 areconstantly meshed with output gear 88 which surrounds transmissionoutput shaft 90.

A two-position synchronized jaw clutch assembly 92, which is axiallypositioned by means of shift fork 94 and the range section shiftingactuator assembly 96, is provided for clutching either gear 88 to outputshaft 90 for low range operation or gear 86 to output shaft 90 fordirect or high range operation of the compound transmission 10. The"repeat H" type shift pattern for compound range type transmission 10 isschematically illustrated in FIG. 1B. Selection and/or preselection oflow or high range operation of the transmission 10 is by means of anoperator actuated switch or button 98 which is usually located at theshift lever 72.

Although the range type auxiliary section 14 is illustrated as atwo-speed section utilizing spur or helical type gearing, it isunderstood that the present invention is also applicable to range typetransmissions utilizing combined splitter/range type auxiliary sections,having three or more selectable range ratios and/or utilizing planetarytype gearing. Also, as indicated above, any one or more of clutches 60,62 or 64 may be of the synchronized jaw clutch type and transmissionsections 12 and/or 14 may be of the single countershaft type.

The main transmission section 12 is controlled by axial movement of atleast one shift rail or shift shaft contained within the shift barhousing 70 and controlled by operation of the shift lever 72. As isknown, shift lever 72 may be mounted directly to, or remotely from, thetransmission. Devices of this type are well known in the prior art andmay be seen by reference to U.S. Pat. No. 4,621,537, the disclosure ofwhich is hereby incorporated by reference. The range section iscontrolled by operation of button 98, or a position switch 98A in thecase of a "double H" type control, both as well known in the prior art.Shift bar housing 70 may also be of the more conventional multiple shiftrail type, well known in the prior art as may be seen by reference toU.S. Pat. Nos. 4,782,719; 4,738,863; 4,722,237 and 4,614,126, thedisclosures of which are incorporated by reference.

The control system of the present invention is equally applicable tocompound transmissions having range, combined range/splitter orsplitter/range type auxiliary sections.

Referring to FIG. 2, compound change gear mechanical transmission 100 isan eighteen forward speed transmission comprising a main transmissionsection 12A, identical, or substantially identical, to main transmissionsection 12 described above in reference to prior art transmission 10.Main transmission section 12A of transmission 100 differs from maintransmission section 12 of transmission 10 only in that main shaft 28Aextends slightly further into the auxiliary transmission section 102than does main shaft 28 extend into auxiliary transmission section 14.In view of the substantially identical structure of main transmissionsections 12 and 12A, main transmission section 12A will not be describedagain in detail.

Auxiliary transmission section 102 includes two substantially identicalauxiliary countershaft assemblies 104 and 104A, each comprising anauxiliary countershaft 106 supported by bearings 108 and 110 in housingH and carrying three auxiliary section countershaft gears 112, 114 and116 fixed for rotation therewith. Auxiliary countershaft gears 112 areconstantly meshed with and support auxiliary section splitter gear 118which surrounds mainshaft 28A. Auxiliary countershaft gears 114 areconstantly meshed with and support auxiliary section splitter/range gear120 which surrounds the output shaft 122 at the end thereof adjacent thecoaxial end of mainshaft 28A. Auxiliary section countershaft gears 116constantly mesh and support auxiliary section range gear 124, whichsurrounds the output shaft 122. Accordingly, auxiliary sectioncountershaft gears 112 and splitter gear 118 define a first gear layer,auxiliary section countershaft gears 114 and splitter/range gear 120define a second gear layer and auxiliary section countershaft gears 116and range gear 124 define a third layer, or gear group of the combinedsplitter and range type auxiliary transmission section 102.

A sliding two position jaw clutch collar 126 is utilized to selectivelycouple either the splitter gear 118 or the splitter/range gear 120 tothe mainshaft 28A, while a two position synchronized assembly 128 isutilized to selectively couple the splitter/range gear 120 or the rangegear 124 to the output shaft 122. The structure and function of doubleacting sliding jaw clutch collar 126 is substantially identical to thestructure and function of sliding clutch collars 60, 62 and 64 utilizedin connection with transmission 10 while the structure and function ofdouble acting synchronized clutch assembly 128 is substantiallyidentical to the structure and function of synchronized clutch assembly92 utilized in connection with transmission 10. Synchronized clutchassemblies such as assemblies 92 and 128 are well known in the prior artand example thereof may be seen by reference to U.S. Pat. Nos.4,462,489; 4,125,179 and 2,667,955, the disclosures of all of which areincorporated by reference.

Such clutches typically include a pair of axially engageable jaw clutchmembers, a sensor/blocker device for sensing nonsynhhronous rotation ofthe jaw clutch members and blocking axial engagement thereof and a pairof friction surfaces, often conical, which are urged into contact tofrictionally connect the jaw clutch members to cause substantiallysynchronous rotation thereof. During attempted engagement of suchassemblies, assuming a substanial nonsynchronous condition, the clutchwill assume a blocked position wherein the blocker device prevents axialengagement of the jaw clutch members and the friction surfaces areengaged under force. If the clutch assembly remains in the blockedposition under a high axial engagement force while the main transmissionis engaged for an extended period of time, excessive torque loading candamage and/or destroy the friction surfaces.

The detailed structure of the preferred embodiment of auxiliary section102 is illustrated in FIGS. 3A and 3B, wherein it may be seen that therearward end of mainshaft 28A extending into the auxiliary transmissionsection 102 is provided with external splines 130 which mate withinternal splines 132 provided on clutch collar 126 for rotationallycoupling clutch collar 126 to the mainshaft 28A while allowing relativeaxial movement therebetween. The clutch collar 126 is provided withclutch teeth 134 and 136 for selective axial engagement with clutchteeth 138 and 140 provided on gears 118 and 120, respectively. Theclutch collar 126 is also provided with a groove 141 for receipt of ashift fork 142.

Gear 118 surrounds mainshaft 28A and is normally free to rotate relativethereto and is axially retained relative to the mainshaft 28A by meansof retainers 144. Clutch teeth 136 and 138 present tapered surfaces 146and 148 which are inclined at about 35° relative to the axis of themainshaft 28A which provides an advantageous interaction tending toresist nonsynchronous engagement and also tending to cause a synchronousrotation as is described in greater detail in U.S. Pat. No. 3,265,173,the disclosure of which is hereby incorporated by reference. Clutchteeth 136 and 140 are provided with similar complementary taperedsurfaces.

Splitter/range gear 120 is rotatably supported at the inward end 150 ofoutput shaft 122 by means of a pair of thrust bearings while range gear124 surrounds the output shaft 122 and is axially retained thereon bymeans of thrust washers. Located axially between gears 120 and 124, androtationally fixed to output shaft 122 by means of external splines andinternal splines, is the double acting two position synchronized clutchassembly 128. Many of the well known synchronized positive clutchstructures are suitable for use in the auxiliary transmission section ofthe present invention. The synchronized clutch assembly 128 illustratedis of the pin type described in above mentioned U.S. Pat. No. 4,462,489.Briefly, the synchronized clutch assembly 128 includes a slidable jawclutch member 162 axially positioned by a shift fork 164 and carryingclutch teeth 166 and 168, respectively, for axial engagement with clutchteeth 170 and 172, respectively, carried by gears 120 and 124,respectively. Gears 120 and 124 define cone friction surfaces 174 and176, respectively, for frictional synchronizing engagement with matchingfrictional cone surfaces 178 and 180, respectively, carried by thefriction rings 182 and 184, respectively, of the synchronized clutchassembly. Blocker pins 186 and 188 are rotationally fixed to thefriction rings 184 and 182, respectively, and interact with blockeropenings 190 carried by the sliding member 162 to provide the blockingfunction as is well known in the prior art. Synchronizing assembly 128may also include a plurality of spring pins (not shown) for providinginitial engagement of the conical friction surfaces at the initiation ofa clutch engagement operation.

Output shaft 122 is supported by bearings 192 in housing H and extendstherefrom for attachment of a yolk member Y or the like which typicallyforms a portion of a universal joint for driving a propeller shaft to adifferential or the like. The output shaft 122 may also carry aspeedometer gear 194 and/or various sealing elements (not shown).

As may be seen by reference to FIGS. 2 and 3, by selectively axiallypositioning both the splitter clutch 126 and the range clutch 128 in theforward and rearward axial positions thereof, four distinct ratios ofmain shaft rotation to output shaft rotation may be provided.Accordingly, auxiliary transmission section 102 is a 3-layer auxiliarysection of the combined range and splitter type providing fourselectable speeds or drive ratios between the input (countershaft 28A)and output (output shaft 122) thereof. Transmissions of this type arewell known in the prior art and are sold by assignee Eaton Corporationunder the trade names "Super 10" and "Super 18" and may be seen ingreater detail by reference to U.S. Pat. No. 4,754,665, the disclosureof which is incorporated herein by reference.

The shift pattern for the transmission 100 is schematically illustratedin FIG. 2A wherein the "S" arrow indicate a splitter shift and the "R"arrow indicates a range shift.

In the preferred embodiment of the present invention, a single shiftshaft type shifting mechanism 200 of the type illustrated in FIG. 4 isutilized. Mechanisms of this type are known in the prior art as may beseen by reference to U.S. Pat. Nos. 4,920,815 and 4,621,537, thedisclosures of which are incorporated herein by reference.

Briefly, shift lever 98 will interact with block member 202 to causerotational or axial movement of shaft 204 relative to the transmissionhousing. Rotational movement will cause keys, such as key 206 andanother unseen key, to interact with lands or slots provided in the hubsof the shift forks 60A, 62A and 64A to axially fix two of the shiftforks relative to the housing and to axially fix the other shift fork toshaft 4. Axial movement of the shaft 204 and the selected shift forkaxially fixed thereto will then result in engagement and disengagementof the jaw clutches associated therewith.

Accordingly, by monitoring of the axial position of a selected segmentof shift shaft 204, such as one or more neutral detent notches 210, thein neutral-not in neutral condition of the main section 12 oftransmission 10 may be sensed.

The present invention is also applicable to compound transmissionsutilizing the well known multiple parallel rail type shift bar housingassemblies as may be seen by reference to U.S. Pat. Nos. 4,445,393;4,275,612; 4,584,895 and 4,722,237, the disclosures of which are herebyincorporated by reference. Such devices typically include an assemblyextending perpendicular to the shift rails (often associated with ashift rail interlock mechanism) which will assume a first position whenall of the shift rails are in an axially centered neutral position or asecond position when any one of the shift rails is displaced from theaxially centered neutral position thereof.

The present invention is also applicable to compound transmissionswherein other mechanical, electrical, electromagnetic or other types ofsensors are utilized to sense conditions indicative of transmission mainsection neutral (not engaged) or not neutral (engaged) conditions.

Although the auxiliary transmission sections are typically attached tothe main transmission section, the term "auxiliary transmission section"as used herein is also applicable to detached drive train devices suchas multiple-speed axles, multiple-speed transfer cases and the like.

While the present invention is equally applicable to transmission 10illustrated in FIG. 1 and transmission 100 illustrated in FIGS. 2 and 3,as well as other compound transmissions utilizing synchronized auxiliarysection jaw clutch assemblies, for purposes of simplification and easeof understanding, the present invention will be described primarily asutilized with the compound range type transmission illustrated in FIGS.1, 1A, 1B and 1C.

Assuming a shift control of the type illustrated in FIG. 1B, i.e. a"repeat H" type control, a 4th-to-5th speed compound shift involvesdisengaging jaw clutch 60 from 4th/8th speed input gear 24, thendisengaging clutch 92 from range low speed or reduction gear 86 andengaging clutch 92 with the high speed or direct range gear 88 and thenengaging jaw clutch 62 with 1st/5th speed main section gear 54. Toaccomplish this, the vehicle operator will preselect "HI" with the rangeselector button 98, will shift from the 4/8 position to N and then tothe 1/5 position with shift lever 72. In prior art range typetransmissions, such as the 9-speed RT/RTO 11609 "Roadranger"transmission manufactured and sold by Eaton Corporation, a two-positionslave valve having a first position for causing "HI" range to beselected and a second position for causing "LO" range to be selected wasinterlocked in one of its two positions by a plunger or the likewherever the main transmission section 10 was not in neutral. Examplesof such valves and interlocks may be seen by reference toabove-mentioned U.S. Pat. Nos. 3,229,551; 4,450,869; 4,793,378 and4,974,474.

As indicated previously, while these devices will, under mostconditions, protect the range section synchronizers by preventinginitiation of a range shift until the main section is shifted intoneutral, under certain conditions the main section shift may completeprior to the range shift which will place the range synchronizer atrisk. This is a considerably greater problem for range upshifts(4th-to-5th) than for range downshifts (5th-to-4th) as torque across thesynchronizer friction cone surfaces (174/178 in FIG. 3A) when engagingdirect range gear 88 will tend to increase the tendency of thesynchronizer being hung up on the synchronizer blockers while torqueacross the friction cone surfaces (176/180 in FIG. 3B) when engagingreduction range gear 86 will tend to pull the synchronizer to anunblocked condition. Generally, in transmissions of the type illustratedin FIGS. 1 and 2, range section synchronizer burn-out is not seen as asignificant problem in range section downshifts.

Referring to the transmission of FIG. 1, another serious problem mayoccur when a driver in 4th gear decides to upshift, then preselects arange upshift and then moves the shift level to or towards the neutralposition. If the driver quickly changes his mind and moves the shiftlever back to the 4/8 position without changing the range selection, therange clutch may attempt to complete a range only 4-8 upshift and thelarge speed differential across the synchornizer cone friction surfacesmay result in rapid damage thereto. In such situations, a synchronizermay be severely damaged or destroyed with two seconds.

Similar inadvertent attempted compound skip upshifts will have similarresults. For another example, if a driver inadvertently preselects orforgets a preselection of a range upshift, and then attempts a 4-3downshift, the actual result will be an attempted 4-7 upshift with alarge speed differential across the synchronizer friction surfaces.

The auxiliary section control system/method of the present inventionminimizes the prior art drawbacks by allowing quicker range shifts.

While the present invention is particularly well suited for use incontrolling the engagement of a synchronized range clutch, especiallythe high speed or direct range clutch of a compound transmission, it isnot intended to be limited to such use and could be useful incontrolling the engagement of synchronized splitter clutches or thelike.

As may be seen by reference to FIGS. 5 and 6, the range clutch actuatorpiston assembly 220 defines a differential area piston 221 having afirst surface area 222 pressurized to engage the low range clutch, and asecond larger surface area 224 pressurized to engage to high rangeclutch with the first level of force. Piston 221 is sealingly andslidably received in a cylinder divided into two chambers 222A and 224A.Piston 221 includes a shaft 226 to which is mounted shift yoke 94 or 164for shifting synchronized clutch 92 or 128 to the selected positionsthereof.

As indicated previously, the not engaged (neutral) and the engaged (notneutral) conditions of the main section (12) of transmission (10) may besensed by sensing axially nondisplaced or displaced positions of themain transmission section shift shaft(s) 204. Such axial displacement ofa shift shaft or shift rail may be sensed on the shaft or rail per se,on an extension thereof, or on a cross-shaft or the like.

The master range valve 232 is connected to a source of filtered andregulated air from filter regulator 234. In heavy-duty vehicles, theregulated air pressure is usually 60 to 80 psi. Switch or level 98 iseffective to either pressurize (Low) or vent (High) the low pressuresignal or pilot line 236. The low range pilot line 236 connects to therange slave valve 238 which is a two-position, four-way valve spring 240biased to the high-speed range position (i.e. chamber 224A pressurizedand chamber 222A exhausted) and responsive to pressurization of pilotline 236 to move to the low-speed range position (i.e. chamber 222Apressurized and chamber 224A exhausted).

An interlock plunger 250 interacts with interlock notch 210 on shiftshaft 204 and interlock notches 252 and 254 on piston 226. The purposeof interlock assembly 256 defined by plunger 250 and notches 250, 252and 254 is to lock the auxiliary range section in either high or lowspeed whenever the main transmission section is not in neutral and tolock the main transmission section in neutral whenever the auxiliaryrange section is not fully engaged in either the high or low speedratios thereof. Interlock assemblies of this type are known in the priorart as may be seen by reference to above-mentioned U.S. Pat. No.4,974,474.

A second, range valve interlock assembly 258 is defined by interlockplunger 260 which interacts with notches 262 and 264 in the slave valve238 and elongated notch 266 on shift shaft 204. The purpose of interlockassembly 258 is to prevent movement of the slave valve 238 in responseto a preselection by master valve 232 if the main transmission sectionremains fully engaged.

Interlock mechanism 258 differs from prior art range valve interlocks inthat notch 266 is considerably axially elongated and will allow theplunger 260 to release the valve 238 as the main transmission section isshifted towards neutral as opposed to the prior art devices which didnot release until a shift completely into main transmision sectionneutral occurred. The advantage of the interlock mechanism 258, ascompared to the prior art, is that if a range shift is preselected andthe main transmission shifted toward neutral, the selected actuatorpiston chambers 222A and 224A will be pressurized or exhausted asrequired allowing the range shift to commence the instant main sectionneutral is reached and the interlock assembly 256 allows movement of thepreloaded piston 221. The above results in a quicker range shift andreduces the possibility of the main transmission section shift beatingthe range and/or the main transmission section being hung up in neutral.

FIG. 5 illustrates the air control system 230 with the range in highspeed ratio thereof. FIGS. 6A-6D illustrate portions of system 230 as ashift in range low speed ratio is preselected and the main transmissionsection is shifted from the currently engaged ratio--into neutral--andthen into engaged in the new ratio thereof.

In FIG. 6A, low range has been preselected by selector 98 and low rangepilot line 236 pressurized. As the shift shaft 204 is in the mainsection fully engaged position, range valve interlock 258 preventsmovement of range valve 238.

In FIG. 6B, shift shaft 204 has begun to move leftwardly as the maintransmission section is shifted towards neutral. Interlock plunger 260is received in the leftward end of interlock groove 266 on shaft 204 anddisengages interlock groove 264 on range slave valve 238 allowing thevalve to move to its low speed ratio position wherein chamber 224A isvented and chamber 222A is pressurized. The piston is prevented fromrightward movement by interlock assembly.

In FIG. 6C, the main transmission section is in neutral, allowingplunger 250 to be received in interlock groove 210 in shift shaft 204and releases to the interlock assembly 256 allowing the piston 221 tomove toward the low speed range thereof. During the auxiliary sectionshift transient, interlock plunger is received in groove 210 to lock themain section in the neutral position thereof.

In FIG. 6D, the range shift into low speed ratio is completed, interlockassembly 258 releases the shift shaft 204 as plunger 250 is received innotch 254 in the piston shaft 226 allowing the main transmission to bereengaged in the desired speed ratio thereof.

While the present invention has been described with a certain degree ofparticularity, it is understood that the present description is by wayof example only and that modification and rearrangement of the parts ispossible within the spirit and the scope of the present invention ashereinafter claimed.

I claim:
 1. A method for controlling a pressurized fluid operated shiftactuator (220) for an auxiliary transmission section (14) of a compoundtransmission (10) including a main transmission section (12) havingengaged and not engaged positions connected in series with saidauxiliary transmission section, said auxiliary transmission sectionincluding a selectable high speed ratio (direct) and a selectable lowspeed ration (reduction), each engageable by a synchronized jaw clutchassembly (92/128), switch means (98/98A) for selecting a desiredauxiliary section ratio, said actuator (220) comprising piston (221)having a first piston surface (224) defining a first chamber (224A) anda second piston surface (222) defining a second chamber (222A),pressurization of said first chamber (224A) and exhaust of said secondchamber causing said actuator to urge said synchronized clutch assemblyto engage said high speed ratio and pressurization of said secondchamber (222A) and exhaust of said first chamber causing said actuatorto urge said synchronized clutch assembly to engage said low speedratio, a common source (234) of pressurized fluid, an exhaust (EX), aslave valve (238) responsive to said switch having a first position forpressurizing said first chamber and exhausting said second chamber and asecond position for pressurizing said second chamber and exhausting saidfirst chamber, a first interlock assembly (256) for preventing movementof said piston when said main transmission section is engaged andpreventing movement of said main transmission section from the neutralposition when said auxiliary section is not engaged in the high or lowspeed ratios thereof, and a control member (204) having a first position(FIG. 6A) corresponding to the engaged position of said maintransmission section and a second position (FIG. 6C) displaced from saidfirst position and corresponding to the not engaged position of saidmain transmission section, said control member assuming a third position(FIG. 6B) intermediate said first and second positions thereof andadjacent said second position thereof as said main transmission sectionis shifted from the engaged position thereof toward the not engagedposition thereof by an amount not sufficient to release said firstinterlock assembly (256) said method comprising:using a second interlockassembly (258) independently operable of said first interlock assembly,interlocking said slave valve (238) to prevent movement between thefirst and the second positions thereof when said control member is inthe first position thereof and allowing movement of said slave valvewhen (i) said control member is in the second position thereof and when(ii) said control member is in the third position thereof.
 2. The methodof claim 1 wherein said fluid is compressed air.
 3. The method of claim1 wherein said auxiliary section is a range section.
 4. The method ofclaim 2 wherein said auxiliary section is a range section.
 5. A system(230) for controlling a pressurized fluid operated shift actuator (22)for an auxiliary transmission section (14) of a compound transmission(10) including a main transmission section (12) having engaged and notengaged positions connected in series with said auxiliary transmissionsection, said auxiliary transmission section including a selectable highspeed ratio (direct) and a selectable low speed ratio (reduction), eachof said auxiliary section ratios engageable by a synchronized jaw clutchassembly (92/128), switch means (98/98A) for selecting a desiredauxiliary section ratio, said actuator (220) comprising a differentialarea piston (221) having a first piston surface (224) defining a firstchamber (224A) and a second piston surface (222) defining a secondchamber (222A), said first piston surface area being larger than saidsecond piston surface area, pressurization of said first chamber (224A)causing said actuator to urge said synchronized clutch assembly toengage said high speed ratio and pressurization of said second chamber(222A) causing said actuator to urge said synchronized clutch assemblyto engage said low speed ratio, a common source (234) of pressurizedfluid an exhaust (EX), a slave valve (238) responsive to said switchhaving a first position for pressurizing said first chamber andexhausting said second chamber and a second position for pressurizingsaid second chamber and exhausting said first chamber, a first interlockassembly (256) for preventing movement of said piston when said maintransmission section is engaged and preventing movement of said maintransmission section from the neutral position when said auxiliarysection is not engaged in the high or low speed ratios thereof, and acontrol member (204) having a first position (FIG. 6A) corresponding tothe engaged position of said main transmission section and a secondposition (FIG. 6C) displaced from said first position and correspondingto the not engaged position of said main transmission section, saidcontrol member assuming a third position (FIG. 6B) intermediate saidfirst and second positions thereof and adjacent said second positionthereof as said main transmission section is shifted from the engagedposition thereof toward the not engaged position thereof by an amountnot sufficient to release said first interlock assembly (256) saidsystem comprising:a second interlock assembly (258) operatingindependently of said first interlock assembly for interlocking saidslave valve (238) to prevent movement between the first and the secondpositions thereof when said control member is in the first positionthereof and allowing movement of said slave valve when (i) said controlmember is in the second position thereof and when (ii) said controlmember is in the third position thereof.
 6. The system of claim 5wherein said fluid is compressed air.
 7. The system of claim 5 whereinsaid auxiliary section is a range section.
 8. The system of claim 7wherein said auxiliary section is a range section.
 9. The system ofclaim 5 wherein said auxiliary section (14) is a two-speed range sectionand said high speed ratio is a direct speed ratio.